Overhead bins are common in the asphalt industry for use as surge bins for receiving the continuous production of asphalt from a portable asphalt plant and holding the same until a truck arrives to take the asphalt away by driving under the bin and loading by gravity. Such bins are well known in the art as disclosed, for example, in U.S. Pat. Nos. 4,482,281 to Musil, 4,465,420 to Dillman, 4,348,146 to Brock and 4,337,014 to Farnham.
These prior art devices comprise a rigid trailer frame, with the bin mounted thereon. In the case of the '014 device of Farnham, the bin and its supporting legs form the rigid trailer frame, essentially having a hitch on one end and wheels on the opposite end.
The bins of Dillman and Farnham are raised to the overhead operating position by pivoting them from a horizontal transport orientation to a vertical operating orientation. In the Brock device, the bin is transported in the operating orientation, and the legs are pivoted from a horizontal to a vertical position to raise the bin to the overhead operating position. The Dillman and Brock devices require the asphalt transporting truck to pass over the lowered trailer frame in order to load from the bin, thus requiring ramps.
The Musil device consists of a rigid frame that is formed to allow the loading trucks to pass under it. During transport the bin is lowered into the frame, occupying the space through which the loading trucks will pass. For operation, jacks are extended down from the frame to support the device on the ground, and the bin is vertically raised by winches and pulleys to a position above the frame.
The above devices also disclose a conveyor for elevating the asphalt from the plant into the bin. This conveyor may be carried on the trailer with the bin, as in the Brock and Musil devices, or on a separate trailer as in the Dillman and Farnham devices.
The above prior art devices are self-erecting, however other such devices are used which are erected with a crane or other external means.
The majority of the prior art in the field has been in the asphalt industry, as discussed above, however such an overhead bin would be valuable in many other situations. Where an operation, such as harvesting grain or other crops, results in a steady stream of product that is removed by trucks or wagons, such an overhead bin would be an asset. Where any bulk material must be stored temporarily, an overhead bin of this type could be beneficial.
The prior art devices are complex, expensive and require time to set up and take down. It is desirable to minimize the time required to convert such a device from the transport mode to the operational mode and back again, as set-up time is down-time, and does not generate income for the operator.
During operation the rigid trailer frame is not utilized in most cases and indeed is in the way, requiring ramps as discussed above. Designing the rigid trailer frame to accommodate the passage of trucks thereunder requires very strong frame members and leads to the need for a complex system of winches to raise the bin to the top of the frame.
An articulating trailer frame, wherein the horizontal frame members of the trailer may be pivoted with respect to each other and act to raise the bin and further act as the legs required to support the bin in the overhead position, would reduce the material required, the weight, the expense and the complexity of the device.